Recovery of oil from tar sands



l /e 12 XR o A. et. All 3's known petroleum deposits of any type.

aecovnav on on. FROM TAR SANDS Todd M. Doscher and Joseph Relsherg,Houston, Tex., assignors to Shell D evelopment Company, New York, N.Y.,a corporation of Delaware N Drawing. Application June 17, 1957 SerialNo. 666,237

12 Claims. (Ci. 166--42) This invention relates to a method for theseparation and recovery of oil from bituminous or tar sands, such asAlberta tar sands, and more particularly pertains to an economical andcommercially feasible method of in situ separation and recovery of highyields of oil from tar sands, such as the Alberta tar sancls in whichthe oil has a density higher than that of water.

In various localities throughout the world, deposits of tar sands orbituminous sands are found; usually the oil or tarry material in thesebituminous sands has a density approaching or even greater than 1.0. Themost extensive and best known deposits of this type occur in theAthabasca district, Alberta Province, Canada. These Athabasca tar sandsextend for many miles and occur in thicknesses varying up to more than200 feet. These tar sands constitute one of the probably largestpresently The oil content of these sands is usually within the range oflO%-20% by weight, although sands with smaller and larger amounts of oilare not unusual; the sands generally also contain small proportions ofwater which is usually in the range of l%-5% by weight. The water ispresent in the form of films surrounding the individual sand grains andinsulating them from the oi; and tar which fills the interstices of themass. The oil or tar from these Athabasca tar sands generally has aspecific gravity varying within the range of from 1.00 to 1.04. TheAthabasca tar sands also have sand particles which are not well rounded.In fact, these sand particles (which are of granitic origin) have acuspidal form or shape.

The oil obtained from the bituminous sands, e.g. the above-describedAthabasca tar sands, is a viscous tarry material which, in its crudestate, does not command a high price. Therefore, any method suitable forrecovering this oil must involve a minimum expense to be attractive forcommercial practice.

Various methods have been proposed heretofore for the extraction andrecovery of the oil from bituminous sands, such as the aforementionedAthabasca tar sands. However, for one reason or another, none of thesehas had any substantial degree of commercial success. In all of thesemethods the operating costs have been so high that these processes havenot been economical for large commercial scale operations. One of themain reasons why the heretofore proposed methods are uneconomical isthat all of them involve the mining and therefore handling of the tarsands for the purpose of recovering therefrom the oily or tarrymaterial. Also, some of these processes involved heating of the tarsands or the use of organic solvents. Thus, in one known process, thetar sand, after removal from the round, is jetted with stentr ...dmulled th :1 small proportion of water at about ht)" mass, and in themaintaining of the circulating water at the desired elevatedtemperature.

Another process involves milling a mined tar sand with kerosene andwater, and then allowing it to settle. A mixture of oil and kerosenefloats to the top of the settling zone, and is removed. The process thusrequires use of an oil solvent (i.e. kerosene) which will have to bedistilled from the extracted oil for reuse. This process is likewiseexpensive, requiring large capital investments and added operatingexpenses for heat.

It is an object of the present invention to obviate the above and otherdefects of the prior art and to provide a process whereby oil in highyields can be recovered from bituminous sands, such as Athabasca tarsands, in situ, i.e. without the necessity of mining these sands, orotherwise handling large masses thereof in order to extract the oil ortarry material therefrom. It is another object of this invention toprovide an economical process for extracting and recovering high yieldsof oil from tar sands without the necessity of heating the sand, or theuse of an oil solvent, or both, the application of at least one of theseprocedures having been heretofore thought to be necessary in order tosecure satisfactory extraction of the oil phase from the sand mass.

The above and other objects are attained, according to the process ofthe present invention, by subje ctjpgthe bituminous sands to the actionof an aqueo h s so l u t ign ii-L 2 is ssrtessas ufiiijuuduseue tion hasa pllwaw More specifically stated, tlTein'Vention comprises contactingthe bituminous or tar sands in situ with an aqueous solution having a pHof at least 12 and containing an effective amount of a non-ionicsurfactant. It has been found that if the pH of the aqueous liquid is atleast 12, the amount of oil or tarry material which may be recoveredfrom a given tar sand is materially greater than when an equiv alentamount of aqueous liquid having a pH material below 12, even thoughcontaining the same non-ionic detergent, is used. It has been stillfurther found that the extraction or recovery of oil from tar sands(other conditions being equal) is further materially improved by theincorporation into the aforementioned highly basic aqueous solutionscontaining the non-ionic surfactant, of minor amounts of neutral saltswhich are chemically nonreactive with the non-ionic surfactants ordetergents. Although there is no in ention to be limited by any theoryof the case, it is presently believed that the use of nonionicsurfactants in a water solution having a pH of at least 12 effects anextraction of most if not all of the oil or tarry material from a tarsand by reason of the ready and spontaneous emulsitication which occurswhen this aqueous liquid comes in contact in situ with the tar in thesands. In this connection it must be noted that crude petroleum oil, asdistinguished from oil from bituminous (tar) sands, will not bespontaneously emulsified when brought in contact with the aforesaidaqueous liquid having a pH of 12 or above and containing a nonionicsurfactant, but requires agitation for emulsification.

A wide variety of non-ionic surfactant compounds may be used in theprocess of the present invention. The following are exemplary classes orgroups of compounds which are effective non-ionic surfactants:

(I) Oil-soluble monohydric alcohols, cg. the octanols, nonanols,decanols, undccanols, dodecanols and the higher aliphatic alcohols.These may be synthetic alcohols, cg. alcohols produced by the so-cnlledOxo process, or they may be of natural origin, eg. fatty alcohols fromsperm oil. Also oil-soluhle aromatic and cyclonliphutie alcohols such asbcnzyl alcohol and methylcyclohexanol may be used.

(ll) Oil-soluble dihydric alcohols such as the hexyleue sunsrl IUTE roanissme COPY aesaa /s glyc'ol's, octyle3 glycols, decylene glycols andthe higher the mono-esters or ethers of polyethylene glycols such as themono-oleate or stearate of noun-ethylene glycol. The commerciallyavailable mixtures of compounds of the aforesaid types may be used.

A particularly desirable non-ionic surfactant for use in the process ofthe present invention (in conjunction with water containing a basiccompound to raise the pH to at least 12) is a glycol or polyglycol etherof the type obtainable by causing an aromatic or hydroaromatic hydroxylcompound substituted in the nucleus by at least one hydrocarbon radicalor equivalent thereof, containing at least four carbon atoms, to reactwith an alpha, beta-alkylene oxide, such as ethylene oxide, propyleneoxide, butylene oxide, or the like. Either or both reactants may firstbe block homopolymerizcd before reacting with each other.

The following are illustrative examples of non-ionic surfactants of thelast-mentioned group: Reaction product obtained by condensing iscroctylphenol with ethylene oxide in a mol ratio of 1:10 (this product iscommercially sold by Rohm and Haas as Triton X-lOO); nonyl phenyl whichhas been oxyethylated with about 30 mols of ethylene per mol of phenol(this is sold commercially by General Aniline and Film Company under thename Antarox A403") an alkyl phenol having an alkyl side chain of 8 or 9carbon atoms, which has been oxyethylated with about 10 mols of ethyleneoxide per mol of phenol (Hercules Powder Companys Synthetic B Thenon-ionic surfactant should be present in the treating or extractingliquid in sufiicient concentration to effect the instantaneous orspontaneous emulsification of the oil or tarry material present in thetar sands and to maintain it in emulsified state during passing throughthe formation and subsequent mechanical handling. Concentrations of fromabout 0.1% by weight to about by weight are usually suilicient for thispurpose, although smaller or larger quantities may be desired or evennecessary in some cases. Excessive concentrations are in most instancesto be avoided as wasteful, or as inimical to proper emulsification, oras yielding an. emulsion too stable to be amenable to its ultimateresolution.

It was pointed out above that the surfactant-containing aqueous liquidmust have a pH of at least 12. This is generally effected by theincorporation of a base to either fresh or saline water. In the case ofdistilled water, a very small amount of a base, e.g. alkali metalhydroxide or ammonia, is required to produce such solution, this amountbeing less than 0.04% by weight. However, in the case of water availablein the field, considerably larger concentrations of base are usuallyrequired to insure the overcoming of the buffering action of compoundsin solution in such waters. As stated, the treating solutions (intowhich the aforementioned non-ionic surfactants are incorporatcd)preferably comprise fresh or saline waters containing ammonia or analkali metal hydroxide, preferably sodium hydroxide, to yield a solutionhaving a pH of at least about 12; normally, this is attained by theincorporation of sodium hydroxide in amounts equal to about 0.5% byweight.

The spontaneous emulsiiication, and therefore the re- 'coverable yieldof oily matter from the tar sands, is enhanced by the presence, in theaqueous non-ionic-surfactant-containing alkaline solution, of awater-soluble A. Generally, water-soluble alkali metal halides,sulfates, carbonates, phosphates, and the like are suitable for use forthis purpose, the amount thereof in the solution ranging fromsubstantially negligible amounts to as high as about 5% by weight,although still larger amounts may be sometimes desirable or evennecessary.

The temperature of the treating solution may vary within wide limits. Asstated, no special heating thereof is necessary. 'Ihus, excellentresults can be obtained by using these aqueous alkaline solutions attemperatures in the range of from about 15 C. to about 40 C. However itmust be noted that sometimes higher temperatures may be advantageousbecause a rise in temperature generally enhances the activity of thesurfactant and thus increases the speed of emulsification.

The process of the present invention comprises or includes three actualoperating steps: (a) an aqueous alkaline treating solution (of a pH ofat least 12) containing a non-ionic surfactant and, optionally awater-soluble neutral inert inorganic salt, is injected into a tar sand;(b) the emulsion formed in situ and containing the oil or tarrymaterial, is brought to the surface, e.g. bypumping; and (c) theemulsion is separated to yield the oil and to recover the treatingsolution for reuse.

In operating on undisturbed tar sand formations in situ, theaforementioned aqueous alkaline surfactant-containing solution may beforced through the formation to effect a recovery of the tarry materialfrom the sands. By sinking a central pressuring or input well in theformation, and around it sinking several other collectng or productionwells, the aqueous solution may be forced down the central well and bymeans of applied pressure cause it to migrate to the neighboringcollecting wells. In the passage of the aqueous solution through the tarsands, the oily or tarry material is stripped free from the sand andemulsified in the form of small discrete particles surrounded by theaqueous solution; in other words, the emulsion formed is of theoil-in-water type.

In operation according to the process generally described in thepreceding paragraph, the introduction of the treating solution into theformation may be interrupted when this solution has penetrated as far asthe production well or wells, this for a period of time sufficient toassure complete emulsification and, thus, recovery of the tarry materialfrom the sand.

Another way of effecting the recovery of oil from tar sand formations,particularly when they are unconsolidated, is to employ a processanalogous to the Frasch process for mining sulfur. In this process asingle well is used, this well being provided with an outer casing setin the well and open to the formation, and an inner tubingconcentrically disposed within the casing and preferably having a nozzleor nozzles at or near its (the tubings) lower end. The aforementionedaqueous alkaline solution is then jetted against the oil-containing tarsand formation through the nozzles; this produces the emulsion, which,together with the entrained sand, is pumped, or otherwise raised to thesurface through the annular space between the casing and the tubing. Ifthe specific gravity is too high and the pumping of the emulsion is toodifficult, other means, e.g. gas lift, may be employed to elevate theoil-containing emulsion to the surface.

In some cases, particularly where the aqueous solution will permeate thetar sand formation only with difiiculty, it may be preferred to use asurging or pulsating motion of the aqueous alkaline solution to effectthe contact thereof with and cmulsiflcation of the oily material at theouter bounds of the zone penetrated by the aqueous solution, andsubsequently provides for the removal of this relatively concentratedemulsion, cg. like in the aforementioned modilied Frasch process, andthe replacement thereof by a fresh or less concentrated solution. Inthis case, if a single well is used, the injections and withdrawal areintermittent and alternate.

In demonstrating the present invention, series of up ansaeva paratuswere set up to simulate conditions in a tar sand formation. Eachapparatus consisted of a glass tubing 4 inches in length and 1 inch indiameter, the tops and bottoms of these tubings being closed byperforated metal discs and screens. Each unit was filled with Althabascatar sand, which was maintained in cold storage since its removal fromthe source, this sand being tamped into the glass cylinders. The oilcontent of this tar sand, as determined by extraction with benzene in asoxhlet extract, was equal to 15.75% by weight (based on the sand).

The various units prepared as described above were then treated bysaturating the sands therein with various aqueous solutions mentionedbelow, and left undisturbed except for the periodic removal of 25 cc.samples of the solute from each and the immediate replacement thereofwith fresh solutions of equal volume. In all, in each case 300 cc. ofthe given aqueous solution were thus passed through the sand in eachvessel, this over a period of 35 days. This was then followed by a washwith a 5% aqueous sodium chloride solution to remove remainingsurfactant from the pack. The effectiveness of each solution to removethe oily material was then determined by extracting the residual tarsremaining in the sands with benzene in a soxhlet extractor. The resultsof these runs are presented in the following table:

The Triton X-lOO is the Rohm and Haas surfacant produced by reactingisooctyl phenol with ethylene oxide in a molar ratio of 1:10.

It will be seen that the use of an aqueous solution containing onlysodium hydroxide did not extract any oil; in fact, the 2% NaOH solutionshowed no signs of even discoloration. Likewise an aqueous solutioncontaining Triton X-lOO (together with some neutral salt) failed toextract any oil, while the use of the same solution with some sodiumhydroxide permitted a substantial oil recovery which was enhanced by thepresence of some sodium chloride. It must also be noted that the use ofan anionic surfactant (sodium lauryl sulfate) failed to result in anysubstantial oil displacement even though the solution also was highlybasic due to the presence of sodium hydroxide.

In another series of tests, using the same size glass tube units and thesame Althabasca tar sand, the following aqueous solutions were -in totalamounts of 100 cc., the passage being in 2 5 cc. increments each ofwhich was allowed to remain in contact with the sand for two days. Theresults of these tests are presented in the following The Igepal CO-850is a full equivalent of the Autarox A-403 discussed above. It must benoted that the use of bornx together with a non-ionic surfactant failedto effect any economical removal of oil from the tar sands; this isbelieved to be due to the fact that borax forms a Q; buffered solutionhaving a pH of only 9.2 even though borax is added in amounts up tosaturation. On the othe hand effective extraction is and was obtained byusing an aqueous alkaline solution having a pH of above 12 (by use ofsodium hydroxide).

The foregoing exemplary description of this invention is not to beconsidered as limiting since many variations may be made within thescope of the following claims by those skilled in the art withoutdeparting from the spirit thereof.

We claim as our invention:

1. The process of recovering oil from oil-containing tar sands whichcomprises contacting tar sands in the formation with an aqueous solutionhaving a pH of at least 12 and containing a non-ionic surfactant,thereby extracting the oil from the tar sands by spontaneousemulsification thereof in the aqueous solution, recovering the emulsionthus formed from the formation, and separating the oil from saidemulsion.

2. The process of recovering oil from oil-containing tar sands whichcomprises contacting tar sands in situ in the formation with an aqueoussolution having a pH of at least 12 and containing at least 0.1% byweight of a nonionic surfactant, thereby extracting the oil from the tarsands by spontaneous emulsification thereof in the aqueous solution,recovering the emulsion thus formed from the formation, and separatingthe oil from said emulsion.

3. The process of recovering oil from oil-containing tar sands whichcomprises contacting tar sands in situ in the formation with an aqueoussolution having a pH of at least 12 and containing between about 0.1%and about 5%, by weight, of a non-ionic surfactant, thereby extractingthe oil from the tar sands by spontaneous emulsification thereof in theaqueous solution, recovering the emulsion thus formed from theformation, and separating the oil from said emulsion.

4. The process according to claim 3, where the nonionic surfactant is areaction product obtained by condensing an alkyl phenol with an alkyleneoxide in an amount of between about 10 and about 30 mols of the alkyleneoxide per mole of the alkyl phenol.

5. The process of recovering oil from oil-containing tar sands whichcomprises contacting a tar sand in situ in the formation with an aqueoussolution containing between about 0.l% and about 5%, by weight, of anonionic surfactant and of a water-soluble alkali metal hydroxide in anamount sufficient to bring the pH of the aqueous solution to at least12, to effect an extraction of the oil from the tar sands and thespontaneous emulsification of said oil in the aqueous solution, therebyproducing an oil-in-watcr emulsion, recovering said emulsion from theformation, and separating the oil from said emulsion.

6. The process according to claim 5, wherein the watersoluble alkalimetal hydroxide is sodium hydroxide.

7. The process according to claim 2 wherein the aqueous solution alsocontains a water-soluble neutral salt which is chemically non-reactivewith the non-ionic surfactant.

8. The process of recovering oil from oil-containin tar sands whichcomprises contacting a tar sand in situ in the formation with an aqeuoussolution containing an alkali metal hydroxide in an amount sutficient toraise the pH of the solution to at least 12, a non-ionic surfactant inan amount equal to between about 0.1% and about 5% by weight, and awater-s oluble neutral salt chemically nonreactive with the non-ionicsurfactant, said salt being used in an amount of up to about 5%, byweight, of the aqueous solution, to effect an extraction of the oil fromthe tar sands and the spontaneous emulsilication of said oil in theaqueous solution, thereby producing an oil-in-water emulsion, recoveringsaid emulsion from the formation, and separating the oil from saidemulsion.

9. The process of recovering oil from oil-containing tar sands whichcomprises introducing into the tar sand formation an aqueous alkalinesolution having a pH of at least 12 and containing at least 0.1%. byweight, of a nonionic surfactant, maintaining said aqueous solution incontact with the tar sands in the formation for a period of timesufficient to eliect an extraction of the oil from the tar sands and thespontaneous emulsiiication of said oil in I containing between about0.1% and-about 5% of a nonionic surfactant up to about 5% of a neutralinorganic salt non-reactive with the surfactant, and an alkali metalhydroxide to bring the pH of the aqueous solution to at least 12,forcing said solution through the tar sand formation thereby extractingoil therefrom and causing said oil to be emulsified in the aqueousalkaline solution, recovering said emulsion through a recovery well at adistance from the injection well, and separating the oil from theemulsion.

ll. The process of recovering oil from oil-containing assaera tar sandswhich comprises introducing into the tar sand formation an aqueoussolution containing an alkali metal hydroxide in an amount sufiicicnt toraise the pH of the solution to at least 12, and containing a non-ionicsurfactant in an amount equal to between about 0.1% and about 5% byweight, maintaining said aqueous solution in contact with theoil-containing tar sands in the formation for a period of timesuilicient to effect an extraction of the oil from the tar sands and thespontaneous emulsification of said oil in the aqueous solution, therebyproducing an oil-in-water emulsion, recovering said emulsion from theformation, and separating the oil from said emulsion.

12. The process according to claim 11 wherein the alkali metal hydroxideis sodium hydroxide.

References Cited in the file of this patent UNITED STATES PATENTS2,412,765 Buddrus et al Dec. 17, 1946 2,748,080 Newcombe et al May 29,1956 2,817,635 Goldman et a1. Dec. 24, 1957

1. THE PROCESS OF RECOVERING OIL FROM OIL-CONTAINING TAR SANDS WHICHCOMPRISES CONTACTING TAR SANDS IN THE FORMATION WITH AN AQUEOUS SOLUTIONHAVING A PH OF AT LEAST 12 AND CONTAINING A NON-IONIC SURFACTANT,THEREBY EXTRACTING THE OIL FROM THE TAR SANDS BY SPONTANEOUSEMULSIFICATION THEREOF IN THE AQUEOUS SOLUTION, RECOVERING THE EMULSIONTHUS FORMED FROM THE FORMATON, AND SEPARTING THE OIL FROM SAID EMULSION.